1) A 67-year-old man is brought to the physician because of a 2-day history of double vision and drooping of his left eyelid. He has no history of trauma to the eye. His vital signs are within normal limits. Physical examination shows ptosis of the left eyelid. When the eyelid is raised manually, the eye is fixed in the out position and the pupil is dilated. The visual acuity of the left eye is within normal limits. Which of the following is the most likely cause of these findings?

Aneurysm of the posterior communicating artery
Compression of the superior cervical ganglion
Damage to the trochlear nerve
Occlusion of the scleral venous sinus
Tumor of the optic nerve